SSRIs are widely used antidepressant agents which are known to decrease platelet serotonin content. They have been reported to be associated with bleeding in a minority of patients and recently have been associated with an increase in gastrointestinal bleeding. The purpose of this study is to better understand the potential risks of bleeding associated with mild platelet dysfunction in patients using SSRIs and to determine whether a global test of platelet function, as performed on the platelet function analyzer-100, is able to identify the changes in platelet function associated with SSRI use. We have completed accrual on this project and are in the midst of data analysis.